Recirculation type exhaust gas cleaning system

ABSTRACT

Recirculation type exhaust gas cleaning system comprising a turbine driven by the output air of an air pump and adapted to drive a blower for directing a part of the exhaust gas into an air cleaner or a carburetor provided in an engine intake system, whereby the maximum temperature in the engine cylinder is reduced and therefore the nitrogen oxide content in the exhaust gas can be decreased.

United States Patent 1451 Nov. 27, 1973 Nohira et a].

[ RECIRCULATION TYPE EXHAUST GAS CLEANING SYSTEM [56] References Cited [75] Inventors: Hidetaka Nohira, Susono; Hiroaki UNITED STATES PATENTS Nishimura, Kariya, both of Japan 3,417,562 12/1968 Morris 60/307 3,570,240 3 1971 Melchior... 60/280 ASSIgHeeSI pf 6 f w Kaflya-Shl, 3,559,402 2/1971 Stone 60/279 Alchl-ken; y a Jldosha gy 3,672,340 6/1972 Bomba 123/119 A Kabushiki Kaisha, Toyota-cho, :LlQI'EFIQlL QQELQ J P V rim ry Examiner-Douglas Hart [22 Filed: g AttorneyJohn Malley et 21 App]. N6; 282,662 57; ABSTRACT Recirculation type exhaust gas cleaning system com- [30] Foreign Application Priority Data prising a turbine driven by the output air of an air Aug 23 1971 Japan 46/6429, pump and adapted to drive a blower for directing a part of the exhaust gas into an air cleaner or a carbu- [521 LS Cl 60/278 60/297 60/307 retor provided in an engine intake system, whereby 153/119 the maximum temperature in the engine cylinder is re- [51] Int Cl F02. 25/06 F02) 75/10 duced and therefore the nitrogen oxide content in the [58] Field of Search. 60/278, 289, 307, exhaust gas can be decreased- 5 Claims, 1 Drawing Figure RECIRCULATION TYPE EXHAUST GAS CLEANING SYSTEM BACKGROUND OF THE INVENTION The present invention relates to a recirculation type engine exhaust gas cleaning system and more particularly to such an engine exhaust gas cleaning system comprising a blower driven by an output air of an air pump for recirculating a portion of exhaust gas from an exhaust pipe into air intake system, such as an air cleaner or a carburetor of an engine so as to reduce the maximum temperature in the engine combustion chamber to minimize the nitrogen oxide content in the exhaust gas.

It has been known that the nitrogen oxide content in engine exhaust gas has a close relation to the maximum temperature in combustion chamber and it has already been proposed to recirculate a portion of the exhaust gas into engine intake system for minimizing the nitrogen content in the exhaust gas.

Conventional recirculation type exhaust gas cleaning system of this kind comprises an exhaust gas cooler through which the recirculation flow of the exhaust gas is passed before it is introduced into the engine intake system. In this type of system, the cooler is often clogged by powders of copper and carbon in the exhaust gas or corroded by water or sulfuric acid contained in the exhaust gas. Further, in order to remove the powders, water and sulfuric acid in the exhaust gas, it is usually required to provide a filter which adversely increases the flow resistance in'the cleaning system. When such a filter is provided, it is necessary to feed the recirculation flow of the exhaust gas under pressure in order to overcome the flow resistance of the filter and, if a motor-driven blower is used for this purpose, a high-speed motor of about 40,000 rpm. must be used for attaining a necessary pressure rise. Therefore, the system requires an increased cost.

SUMMARY OF THE INVENTION The present invention eliminates the above disadvantages of prior art by providing a turbine driven by an output air of an air injection pump for driving an exhaust gas recirculation blower, Thus, the blower can be driven at a high speed by said turbine so as to recirculate a portion of exhaust gas from the exhaust pipe into the air intake system of the engine.

More particularly, according to the present invention, the turbine is driven at a high speed by the output air of the air injection pump and, at the same time, foreign particles, water and sulfuric acid are removed by a filter provided in the exhaust gas. A portion of the exhaust gas which has passed through the filter is then recirculated into the engine air intake system, such as an air cleaner or a carburetor by means of a blower connected to the output shaft of said turbine. Thus, the

BRIEF DESCRIPTION OF THE DRAWING The drawing diagrammatically show an embodiment of the recirculation type exhaust gas cleaning system in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, the reference numeral I designates an air cleaner for an automobile engine, 2 a carburetor, 3 an air intake manifold, 4 an intake valve, 5 a cylinder, 6 an exhaust valve, 7 an exhaust manifold and San exhaust pipe, and there is provided a filter 9 in the exhaust pipe 8. The reference numeral I0 designates an air injection pump having an air intake passage 10a connected to the air cleaner 1 and an outlet passage l0b connected to the air intake passage Ila of a turbine 11. The turbine 11 is in turn connected by its outlet passage 11b to an air distribution manifold 12. The manifold 12 is further connected to an air injection pipe 13 projecting into the exhaust manifold 7. The reference numeral 14 designates a blower driven by the turbine 11, and 15 a rotatable shaft connecting the turbine 11 with the blower 14. The blower 14 has an exhaust gas inlet passage 14a connected to the exhaust pipe 8'at the downstream side of the filter 9 and an exhaust gas outlet passage 14b connected through a valve 16 to the air cleaner 1. The filter 9 may comprise, for example, a cyclone separator 9a for separating relatively raw particles and a filtering layer 9b made of steel wool or the like.

The system of the present invention constituted as described above operates as follows. The air pump 10 which is driven by an engine crankshaft through a belt drive device serves to feed cleaned air from the air cleaner 1 into the inlet passage 11a of the turbine 11.

Thus, the turbine 11 is operated at a high speed by the air. The air which has passed through the turbine 11 is introduced into the air distribution manifold 12 and then into the injection pipe 13. Thus, cleaned air is injected into the exhaust gas manifold 7 at a portion adjacent to the exhaust valve 6, whereby recombustion of the exhaust gas takes place reducing harmful combustion products. The exhaust gas is further introduced through the exhaust manifold 7 and the exhaust pipe 8 into the filter 9 where particles of copper, carbon and the like are removed from the exhaust gas. At the same time, the exhaust gas is cooled so as to reduce the content of water, sulfuric acid and the like in the exhaust gas.

7 A portion of the exhaust gas cleaned by the filter 9 as described above is then drawn by .the blower 14 which is connected to the turbine 11, and pressurized to a desired value, for example about 50 mmHg, to be introduced into the air cleaner 1. Then, the portion of the exhaust gas is mixed with the mixture in the carburetor 2 and introduced into the cylinder 5 of the engine. The recirculated portion of the exhaust gas is efi'ective to reduce the maximum temperature in the cylinder 5 preventing nitrogen oxide from being produced. The valve 16 serves to control the flow of the recirculation gas in accordance with the speed of theautomobile or the temperature of the engine. For example, the valve 16 may be opened at the vehicle speed of km/H or below and the temperature of the cooling medium of the engine is between 65 and C. The control is performed for the purpose of reducing the nitrogen oxide content in the exhaust gas without producing any adverse effect on the operation of the engine.

Although the above embodiment is believed to be a preferred one, the invention is not limited to the detail of the embodiment but various changes and modifications can be made without departing from the scope of the present invention. For example, the portion of the exhaust gas recirculated by the blower 14 should not necessarily be introduced into the air cleaner 1 but may be into the carburetor 2 at the upstream side of throttle valve. Further, the outlet passage a may be divided into two passages, one being connected to the air distribution manifold 12 as shown by a dotted line in the drawing, and the other being connected to the inlet passage 11a of the turbine 11 with the air outlet passage llb of the turbine 1] opened to the atmosphere as shown by a dotted line.

As described above, according to the present invention, foreign particles, water content and sulfuric acid are removed by the filter 9 provided in the exhaust pipe 8 and sufficiently cooled portion of the exhaust gas is recirculated into the air cleaner 1 or the carburetor 2 of the engine intake system by a blower 14 operated by a turbine which is in turn driven by an output air of the air pump 10. Therefore, the mechanical components such as the carburetor 2, the blower 14 and the valve 16 can be free from clogging or corrosion by water content or sulfuric acid, so that the life of the mechanical components can be remarkably increased. The arrangement in which the blower 14 is driven by a high speed turbine which is operated by an output air from an air pump 10 is effective to provide a desired exhaust gas cleaning system at a reduced manufacturing cost.

We claim:

1. A recirculation type exhaust gas cleaning system for an internal combustion engine having intake and exhaust pipes comprising,

an air cleaner connected with said intake pipe for cleaning the air to be supplied to said intake pipe, an air pump connected with said air cleaner for sup plying the air to the exhaust pipe by compressing the air to be supplied from said air cleaner,

a turbine having an output shaft disposed to be driven by the compressed air of said air pump,

a blower connected to the output shaft of said tur bine,

filter means provided in said exhaust pipe for removing foreign particles in the exhaust gas after the air from said air pump has been supplied, and a conduit means for recirculating a portion of the exhaust gas, which has passed through said filter means into the intake pipe of the engine by said i blower.

2. An exhaust gas cleaning system in accordance with claim 1 wherein said air cleaner is connected with said conduit means for cleaning the recirculated exhaust gas from said conduit means and supplying the same to said intake pipe.

3. An exhaust gas cleaning system in accordance with claim 1 further comprising,

a carburetor provided between said air cleaner and said intake pipe and communicated to said conduit means, thereby the air and the recirculated exhaust gas are supplied to the intake pipe through said carburetor.

4. An exhaust gas cleaning system in accordance with claim 1 wherein all of the compressed air from said air pump is supplied through said turbine to said exhaust pipe.

5. An exhasut gas cleaning system in accordance with claim 1 wherein some part of the compressed air from said air pump is supplied to said exhaust pipe and the rest of the part to said turbine. 

1. A recirculation type exhaust gas cleaning system for an internal combustion engine having intake and exhaust pipes comprising, an air cleaner connected with said intake pipe for cleaning the air to be supplied to said intake pipe, an air pump connected with said air cleaner for supplying the air to the exhaust pipe by compressing the air to be supplied from said air cleaner, a turbine having an output shaft disposed to be driven by the compressed air of said air pump, a blower connected to the output shaft of said turbine, filter means provided in said exhaust pipe for removing foreign particles in the exhaust gas after the air from said air pump has been supplied, and a conduit means for recirculating a portion of the exhaust gas which has passed through said filter means into the intake pipe of the engine by said blower.
 2. An exhaust gas cleaning system in accordance with claim 1 wherein said air cleaner is connected with said conduit means for cleaning the recirculated exhaust gas from said conduit means and supplying the same to said intake pipe.
 3. An exhaust gas cleaning system in accordance with claim 1 further comprising, a carburetor provided between said air cleaner and said intake pipe and communicated to said conduit means, thereby the air and the recirculated exhaust gas are supplied to the intake pipe through said carburetor.
 4. An exhaust gas cleaning system in accordance with claim 1 wherein all of the compressed air from said air pump is supplied through said turbine to said exhaust pipe.
 5. An exhasut gas cleaning system in accordance with claim 1 wherein some part of the compressed air from said air pump is supplied to said exhaust pipe and the rest of the part to said turbine. 